MIDDLETOWN, Pa. (WHTM) – The mother, uncle, and grandfather of a 3-year-old girl who drowned in a home swimming pool last summer are headed to trial.

All charges against 23-year-old Tiffany M. Graham, 18-year-old Austin Biller, and 53-year-old Craig Biller were bound for court after a preliminary hearing Wednesday, according to court records.

Graham’s daughter died July 31 at Penn State Hershey Medical Center after she was found in a pool near the Billers’ home in Lower Swatara Township.

Graham and her brother are charged with involuntary manslaughter and endangering the welfare of children. Her father is charged with tampering with evidence and hindering apprehension. Authorities say he removed the girl’s clothing from the poolside to keep it from investigators.

Austin Biller told investigators he fell asleep while his niece was in a high chair and she was gone when he awoke. He said he searched the house and drove throughout the neighborhood looking for her, but police said he didn’t call 911 to report her missing until emergency vehicles arrived in the area more than an hour later.

Graham is accused of putting her daughter in an unsafe place because the girl had wandered off before while in his care.

In May 2015, prosecutors said Graham’s daughter was found wandering and crossing streets alone while in her brother’s and father’s care, and both men were babysitting the girl in December 2015 when police said she walked outside alone for about 30-40 minutes wearing only a diaper.

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